Toothpaste compositions are discussed generally in U.S. Pat. Nos. 4,048,300; 2,839,448; 5,614,175; 5,279,815; 5,225,177; 4,828,833; 5,670,138; 5,096,698; 5,571,502; 5,240,710; and 5,624,906, the contents of which are incorporated herein by reference. The solid and liquid components in toothpaste compositions are formulated in such a way that the end product is an extrudable creamy mass. The total liquid content in toothpaste is typically about 20%-75% by weight of the formulation. Toothpastes generally contain the following components: an abrasive, a humectant, water between 20%-35%, a detergent, salts, sweetener, color and flavor oil, and a binding reagent. Binding reagents are included in a toothpaste composition to build viscosity. The binder content typically employed is in an amount up to about 10% by weight, and preferably about 0.5%-5% of the formulation.
Two preferred binding reagents for toothpaste are carrageenan and carboxy methyl cellulose (CMC). Use of either binding reagent produces a similarly desirable toothpaste texture. The less expensive CMC is generally preferred, although it suffers from the drawback of being susceptible to degradation by the cellulase enzyme, which is ubiquitously present in tropical climates. Breakdown of CMC by cellulase results in a decrease in the viscosity of the toothpaste which becomes watery. The presence of cellulase in manufacturing areas causes quality control problems in production, and the presence of cellulase in households causes quality problems with the finished paste once the package is opened.
Carrageenan is not degraded by cellulase and is, therefore, favored for its stability in toothpastes produced and used in tropical climates. Thus, in tropical countries, particularly those referred to as developing countries, toothpaste producers must use carrageenan as a binding reagent (at greater than twice the cost as CMC, or an equally expensive alternative such as xanthan).
The carrageenan family has four main branches which are well differentiated in their gelling properties: kappa, iota, lambda, and a hybrid of kappa and iota referred to as kappa-2. The characteristics of the different carrageenan types are listed below:
The different types of carrageenan are obtained from different seaweeds. At present all commercially available lambda carrageenan preparations contain a certain amount of the weak gelling kappa carrageenan (kappa-2), and is thus referred to as kappa-2/lambda carrageenan. The mixture of carrageenan types used in the toothpaste binder affects paste viscosity, paste strength, and paste consistency. Preferred carrageenan binder compositions comprise a blend of refined iota and refined kappa-2/lambda carrageenan types. When processed for use in toothpaste formulations, kappa-2/lambda carrageenan behaves similarly to a pure lambda carrageenan preparation. This blend yields a smooth, soft paste greatly preferred by consumers. The very strong gelling kappa carrageenan is not used in the commercial production of toothpaste as it produces an undesirable texture and promotes syneresis in the toothpaste package.
Toothpaste compositions which contain carrageenan as a binding agent utilize highly purified, relatively expensive, refined preparations. Kappa and iota carrageenan are also commercially available in a less expensive, less pure, semi-refined preparation, however this form of carrageenan has not previously been thought useful in a toothpaste binder.
One aspect of the present invention relates to a toothpaste binder composition comprising semi-refined carrageenan. Examples of semi-refined carrageenan suitable for incorporation into a toothpaste binder are semi-refined kappa carrageenan and semi-refined iota carrageenan.
A toothpaste binder comprising semi-refined kappa carrageenan, semi-refined iota carrageenan, or a combination of both semi-refined kappa and iota carrageenan is preferably comprised of about 10% to about 20% refined kappa-2/lambda carrageenan; about 35% to about 50% refined iota carrageenan; about 20% to about 30% semi-refined kappa and/or semi-refined iota carrageenan; and about 5% to about 20% standardizing agent; by dry weight. Specific formulations incorporating semi-refined carrageenan are provided. Properties and characteristics exhibited by a toothpaste which incorporates the specific binder formulations are also described.
Another aspect of the present invention relates to a toothpaste binder composition comprising a semi-refined carrageenan, such as semi-refined kappa or semi-refined iota carrageenan, further comprising ultra low viscosity guar gum. Such a toothpaste binder composition is preferably comprised of about 5% to about 10% refined kappa-2/lambda carrageenan; about 40% to about 50% refined iota carrageenan; about 20% to about 25% semi-refined kappa and/or semi-refined iota carrageenan; about 10% to about 20% ultra low viscosity guar gum; and about 5% to about 10% standardizing agent; by dry weight.